C# source generated files not emitted in the configured folder

Question

Given the following C# source generator project file:

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <TargetFramework>netstandard2.0</TargetFramework>
      <EnforceExtendedAnalyzerRules>true</EnforceExtendedAnalyzerRules>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="Microsoft.CodeAnalysis.Analyzers" Version="3.3.4">
      <PrivateAssets>all</PrivateAssets>
      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
    </PackageReference>
    <PackageReference Include="Microsoft.CodeAnalysis.CSharp" Version="4.7.0" />
  </ItemGroup>

</Project>

and generator source code:

    [Generator]
    public class HFGen1 : ISourceGenerator {
        public void Execute(GeneratorExecutionContext context)
        {
            StringBuilder sourceBuilder = new StringBuilder(@"
using System;
namespace HelloWorldGenerated
{
    public static class HelloWorld
    {
        public static void SayHello() 
        {
            Console.WriteLine(""Hello from generated code!"");
            Console.WriteLine(""The following syntax trees existed in the compilation that created this program:"");
");

            // using the context, get a list of syntax trees in the users compilation
            IEnumerable<SyntaxTree> syntaxTrees = context.Compilation.SyntaxTrees;

            // add the filepath of each tree to the class we're building
            foreach (SyntaxTree tree in syntaxTrees) {
                sourceBuilder.AppendLine($@"Console.WriteLine(@"" - {tree.FilePath}"");");
            }

            // finish creating the source to inject
            sourceBuilder.Append(@"
        }
    }
}");

            // inject the created source into the users compilation
            context.AddSource("helloWorldGenerated.g.cs", SourceText.From(sourceBuilder.ToString(), Encoding.UTF8));

        }

        public void Initialize(GeneratorInitializationContext context)
        {
        }
    }

and the following addition to the generator target project:

  <ItemGroup>
    <ProjectReference Include="..\HFGen\HFGen.csproj" 
                      OutputItemType="Analyzer"
                      ReferenceOutputAssembly="false" />
  </ItemGroup>
    <PropertyGroup>
        <EmitCompilerGeneratedFiles>true</EmitCompilerGeneratedFiles>
        <CompilerGeneratedFilesOutputPath>Generated</CompilerGeneratedFilesOutputPath>
    </PropertyGroup>    

The result is working EXCEPT:

The generated file is not emitted in "Generated" folder. The "Generated" folder is created, the generated code file is written in a Temp folder (default behaviour without EmitCompilerGeneratedFiles).

What's wrong?